[Feature] Android mobile app (v1)

[thangnm93]

Problem Statement

YourSSH ships on macOS / Windows / Linux only. Users who manage hosts on the go have no way to reach their saved servers from a phone — they must switch to a separate mobile SSH app and re-enter every host. A first-party Android client lets the same hosts (synced from desktop) be reached from a phone.

Proposed Solution

Add Android as a target of the existing app/ Flutter project, shipping a focused mobile SSH client (v1) that reuses the platform-agnostic core (models / providers / services) and adds a mobile UI layer. Delivered as 5 milestones:

• M1 — Target + platform branch: android/ target; main() branches on isMobilePlatform to mount a mobile shell and skip the desktop-only bootstrap (window_manager / hotkey_manager / local_notifier / flutter_pty). Desktop untouched.
• M2 — Hosts + terminal: hosts list + minimal add-host form + connect; mobile TerminalView with an accessory key bar (sticky Ctrl/Alt, ^C/^D, arrows, special chars) and pinch-to-zoom; multi-session strip. Mobile-scoped bootstrap reusing existing providers/services.
• M3 — Host import from desktop: cloud Supabase pull + P2P QR camera scan (mobile_scanner).
• M4 — SFTP + snippets: single-panel SFTP (browse / download / upload via file_picker) + snippets quick-insert sheet. (Command history deferred — no input bar to capture commands on mobile.)
• M5 — Security + polish: biometric app-lock (local_auth), TOFU host-key-mismatch dialog, terminal appearance settings, release APK signing via key.properties.

Specs and per-milestone plans live in docs/superpowers/specs/ and docs/superpowers/plans/.

Alternatives Considered

• Separate mobile app / extracted core package: cleaner long-term but requires a large upfront refactor; chose to add the target to app/ with a mobile-scoped bootstrap (zero desktop-regression risk, ships faster).
• Full feature port (RDP/VNC, port forwarding, DevOps tools): out of scope for v1 — large native (NDK) and background-execution work; deferred.

Additional Context

• New mobile dependencies: mobile_scanner (QR scan), local_auth (app-lock) — accepted bundle tradeoff (single shared pubspec).
• iOS deferred but the structure does not preclude it.
• 33 commits, all milestones TDD-covered (33 new widget/unit tests); debug APK builds green; on-device verification pending a device/emulator.
• PR: targets develop.